It appears the buffering happens only on HBO Max. I am having the same issue as everyone else! Frustrating does not cover it!

Hello, user_zgyf8g, and thank you for being part of the Xfinity Forums community! We know how important it is to enjoy your favorite streaming apps without interruptions, and we’re here to help troubleshoot any buffering issues. To start, check your internet speed and, if possible, switch to a wired Ethernet connection for better stability. Restarting your Gateway can also make a big difference. If buffering continues, try these steps:

Close other devices or background apps using your network.
Lower the video quality in your streaming app.
Restart both your streaming device and the app, then test again to see if performance improves.

We’re here to support you every step of the way—let us know how these steps work for you! 

Massive amounts of buffering and audio cut-outs tonight. The standard steps for resolution presented by Xfinity are garbage and they should be working with HBO to fix the problem. Nothing worse than paying a hefty monthly subscription for 2007 buffering issues and commercials.